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A semi-empirical mechanistic contact law for micro-crystalline cellulose (Avicel PH-200) particles is proposed and characterized experimentally using force-displacement curves obtained from diametrical compression of single particles. The concepts of a shape factor and a master contact law are introduced first for elastic ellipsoidal particles, and subsequently generalized to plastic irregular particles. The proposed loading-unloading contact law is a function of three characteristic diameters (lengths of the principal axes of an approximated ellipsoid), a geometric parameter associated with the loading condition, three plastic and one elastic material properties. The force-displacement curves obtained using a micro-compression tester exhibit an apparent strain-hardening at distinctly different strain values, which is captured by the shape factor function and its geometric parameter. The three plastic material properties are log-normal distributions estimated from the loading experimental curves, while the elastic property is estimated from the unloading experimental curves. The study shows a very good agreement between predictions of the calibrated loading-unloading contact law and the experimental values.

We present contact radius and curvature corrections to the nonlocal contact formulation that take into account multi-particle interactions in elastic confined granular systems. The nonlocal contact formulation removes the classical assumption of independent contacts by taking into account the interplay of deformations due to multiple contact forces acting on a single particle. The contact radius correction considers the components of these deformations that contribute to the inter-particle contact area. The curvature correction improves the description of the contacting surface profiles by including higher order terms in their Taylor series expansions. To validate the corrected formulation, we restrict attention to rubber spheres under different loading conditions, in the absence of gravitational forces, adhesion or friction. Specifically, we show that the predictions of contact force and radius are in remarkable agreement with finite-element simulations and experimental observations up to levels of deformation at which contact impingement occurs, which was not possible with the original elastic nonlocal contact formulation. Convergence of the curvature corrected formulation is observed at a four-term correction.

Hydro-meteorological variables, like precipitation, streamflow are significantly influenced by various climatic factors and large-scale atmospheric circulation patterns. Efficient water resources management requires an understanding of the effects of climate indices on the accurate predictability of precipitation. This study aims at understanding the standalone teleconnection between precipitation across India and the four climate indices, namely, Ni\~no 3.4, PDO, SOI, and IOD using partial wavelet analysis. The analysis considers the cross correlation between the climate indices while estimating the relationship with precipitation. Previous studies have overlooked the interdependence between these climate indices while analysing their effect on precipitation. The results of the study reveal that precipitation is only affected by Ni\~no 3.4 and IOD and a non-stationary relationship exists between precipitation and these two climate indices. Further, partial wavelet analysis revealed that SOI and PDO do not significantly affect precipitation, but seems the other way because of their interdependence on Ni\~no 3.4. It was observed that partial wavelet analysis strongly revealed the standalone relationship of climatic factors with precipitation after eliminating other potential factors. Keywords: Indian Precipitation, wavelet coherency, partial wavelet coherence, teleconnections patterns., Comment: 28 pages, 14 figures, 4 tables, Article submitted to JOH